The U.S. Ambassador to the United Nations says the United States believes the most appropriate response to North Korea's rocket launch will be to work toward a new U.N. Security Council resolution, but she fell short of guaranteeing tougher sanctions.

She says the United States will work closely with its allies in the Security Council to get a united and firm response against North Korea. "The United States' view is, this is serious, it is a violation, and it merits an appropriately strong United Nations response," she said.

Rice will be representing the United States at an emergency Security Council meeting later Sunday (1900 UTC) to discuss how to respond to North Korea's action.

Although Japan is calling for new sanctions, China, Pyongyang's major ally and a permanent member on the Security Council, has often stood in the way of strong international action. Rice acknowledged that China has been reluctant to pressure North Korea, but says Beijing is no less invested in a peaceful outcome. "China also is very proximate, on the border with North Korea, and shares our desire not to see this situation escalate, and to ensure that we can achieve the long-term goal, which is de-nuclearization of the Korean Peninsula through the six-party talk process," she said.

Rice says the six-party talks have stalled due to the uncertainty that there is a power structure in place to ensure de-nuclearization. North Korea's dictator, Kim Jong Il, is believed to have suffered a stroke last August, but appears to be back in control and reasserting his regime's power.

Rice says the Unites States is committed to preventing North Korea from pursuing and disseminating nuclear weapons. "We view North Korea as a proliferation threat. Its actions today underscore our concern about its development of not only a nuclear weapons capability, but the capability to deliver it," she said.

Ambassador Rice appeared on ABC television.

President Barack Obama also condemned North Korea's actions in a speech on nuclear disarmament in front of a large crowd in the Czech capital, Prague. The Czech Republic and Poland were both planned sites for the previous administration's U.S. missile-defense shield to counter any nuclear threat from Iran, which, like North Korea, is believed to be developing nuclear weapons.

Senior adviser to President Obama, David Axelrod, told "Fox News Sunday" the president is interested in missile defense only if it is necessary and cost effective. "I think he has an obligation not to deploy systems that do not work, but he is not taking it off the table. But our goal should be a world in which you do not need those systems because the weapons have been eliminated, and we have to start down that road," he said.

Axelrod says a better response than missile defense would be for the international body to unite and put pressure on Iran and North Korea to abandon their nuclear ambitions.